• Journal of the Society of Disaster Information
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• v.17 no.3
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• pp.655-666
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• 2021

Purpose: This study is to develop a method for measuring dynamic speeding risks using vehicle trajectory big data and to demonstrate the feasibility of the devised speeding index. Method: The speed behaviors of vehicles were analysed in microscopic space and time using individual vehicle trajectories, and then the boundary condition of speeding (i.e., boundary speed) was determined from the standpoint of crash risk. A novel index for measuring the risk exposure of speeding was developed in microscopic space and time with the boundary speed. Result: A validation study was conducted with vehicle-GPS trajectory big data and ground-truth vehicle crash data. As a result of the analysis, it turned out that the index of speeding-risk exposure has a strong explanatory power (R²=0.7) for motorway traffic accidents. This directly indicates that speeding behaviors should be analysed at a microscopic spatiotemporal dimension. Conclusion: The spatial and temporal evolution of vehicle velocity is very variable. It is, hence, expected that the method presented in this study could be efficaciously employed to analyse the causal factors of traffic accidents and the crash risk exposure in microscopic space using mobility trajectory data.

• Journal of Digital Convergence
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• v.18 no.3
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• pp.163-169
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• 2020

A smart key has been used in a variety of embedded environments and there also have been attacks from a remote place by amplifying signals at a location of a user. Existing studies on defence techniques suggest multiple sensors and hash functions to improve authentication speed; these, however, increase the electricity usage and the probability of type 1 error. For these reasons, I suggest an embedded security controller based on client authentication and user movement information improving the authentication method between a controller and a host device. I applied encryption algorithm to the suggested model for communication using an Arduino board, GPS, and Bluetooth and performed authentication through path analysis utilizing user movement information for the authentication. I found that the change in usability was nonsignificant when performing actions using the suggested model by evaluating the time to encode and decode. The embedded security controller in the model can be applied to the system of a remote controller for a two-wheeled vehicle or a mobile and stationary host device; in the process of studying, I found that encryption and decryption could take less then 100ms. The later study may deal with protocols to speed up the data communication including encryption and decryption and the path data management.

• Journal of Positioning, Navigation, and Timing
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• v.6 no.1
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• pp.17-26
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• 2017

Latency occurs in RTK, where the measured position actually outputs past position when compared to the measured time. This latency has an adverse effect on the navigation accuracy. In the present study, a system that estimates the latency of RTK and compensates the position error induced by the latency was implemented. To estimate the latency, the speed obtained from an odometer and the speed calculated from the position change of RTK were used. The latency was estimated with a modified correlator where the speed from odometer is shifted by a sample until to find best fit with speed from RTK. To compensate the position error induced by the latency, the current position was calculated from the speed and heading of RTK. To evaluate the performance of the implemented method, the data obtained from an actual vehicle was applied to the implemented system. The results of the experiment showed that the latency could be estimated with an error of less than 12 ms. The minimum data acquisition time for the stable estimation of the latency was up to 55 seconds. In addition, when the position was compensated based on the estimated latency, the position error decreased by at least 53.6% compared with that before the compensation.

• Journal of Satellite, Information and Communications
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• v.2 no.2
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• pp.64-68
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• 2007

This paper describes the development of RF front.end equipment of a wide band high precision satellite navigation receiver to be able to receive the currently available GPS navigation signal and the GALILEO navigation signal to be developed in Europe in the near future. The wide band satellite navigation receiver with high precision performance is composed of L - band antenna, RF/IF converters for multi - band navigation signals, and high performance baseband processor. The L - band satellite navigation antenna is able to be received the signals in the range from 1.1 GHz to 1.6 GHz and from the navigation satellite positioned near the horizon. The navigation signal of GALILEO navigation satellite consists of L1, E5, and E6 band with signal bandwidth more than 20 MHz which is wider than GPS signal. Due to the wide band navigation signal, the IF frequency and signal processing speed should be increased. The RF/IF converter has been designed with the single stage downconversion structure, and the IF frequency of 140 MHz has been derived from considering the maximum signal bandwidth and the sampling frequency of 112 MHz to be used in ADC circuit. The final output of RF/IF converter is a digital IF signal which is generated from signal processing of the AD converter from the IF signal. The developed RF front - end has the C/N0 performance over 40dB - Hz for the - 130dBm input signal power and includes the automatic gain control circuits to provide the dynamic range over 40dB.

• Journal of Korean Society of Forest Science
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• v.96 no.1
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• pp.7-13
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• 2007

This study was done to develop PDA based application system for forest geographic information with GPS. The major results obtained in this study were as follows. A PDA based application program was developed to work on $Microsoft^{TM}$ PocketPC 2002 and 2003 operating system. The screen of PDA displays a 1:25,000 digital topographical map adopted DXF format converted from PC, and the map data with 1:2,500 to 1:30,000 on PDA can be zoomed in or out to five levels. Current position and navigating path received from GPS can be displayed on the screen and be saved in PDA. Information selected among layers of digital topographic map in DXF format can be converted into binary files which can be used on forest geographic information software. This can compress DXF files to 90% in size, and the processing speed of PDA was improved. The forest geographic information management system can be used to manage sample plots on which forest inventory is done, with the help of the sub-menus and grid index values with position information received from GPS. Forest workers can in quire forest geographic information such as forest type, location, forest roads, soil erosion control dams using forest geographic information management system in the field. The forest geographic information management system can provide current position and mobile path information to people who enjoy forest related activities like mountain-climbing, sightseeing, and visiting to historic spots.

• IEMEK Journal of Embedded Systems and Applications
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• v.1 no.2
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• pp.82-89
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• 2006

It appears that it is possible for us to make a wireless communication of even home-network system within car by integrating with the Ubiquitous such as mobile phone, wireless Internet, GPS and DMB in the future. If the present wireless surroundings within the car are connected with very high-speed wireless network as measurement system for wireless communication surroundings within this car in the future, it will develop the complicated communication conditions such as safe checkup, communication between systems within car, and wireless communication for user entertainment unlike universal communication conditions. Accordingly, there is the necessity of the device that can measure the interference of electric wave, communication speed and communication quality by a kind of each car. This paper aims at making the real measurement device to raise the reliability of each Application for inquiring into the interference about each other in the frequency band used under Telematics surroundings.

• Korean Journal of Agricultural Science
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• v.37 no.1
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• pp.123-130
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• 2010

A steering control system based on CAN(Controller Area Network) for autonomous tractor was developed to reduce duty of a central processing computer and to improve performance of steering control in terms of reduced control interval and error. The steering control system consisted of a SCU (Steering Control Unit), an EHPS system, and a potentiometer. The SCU consisted of an MCU (Micro Controller unit), an A/D converter, and a DC-DC converter, and a PID controller was used to control steering angle. The steering control system was communicated with the computer by CAN-bus. Each actuator and implement was connected to a multi-function board interfacing with the computer through a USB cable. Without CAN, control interval of the autonomous tractor was 1.5 seconds. When the CAN-based steering control system was combined with the autonomous tractor, however, control interval of the integrated system was reduced to those less than 0.05 seconds. When the autonomous tractor was operated with 1.5-s and 0.05-s control cycles at a 0.63-m/s travelling speed, the trajectories were close to straight lines for both of the control cycles. For a 1.34-m/s traveling speed, tractor trajectory was close to sine wave with a 1.5-s control cycle, but was straight line with a 0.05-s control cycle.

• Convergence Security Journal
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• v.8 no.1
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• pp.9-18
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• 2008

This paper propose CAR-TO-CAR protocol which can prevent the cars at high-speed from a multiple clash accident at highway with exchanging information. we construct cluster be linked with distance took from GPS(Global Positioning System) because there is no connection at cars on the road. The proposed method solved the overload problem by establishing route because construct the cluster at the IEEE 802.11 MAC class. 'Multi-hop Routing protocol' based on Active Network enable stable Network to be formed by using Active Network.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.12 no.6
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• pp.273-278
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• 2012

Wired communication signals that are generated in a wheelchair and using GPS to gather speed in this study. And occupants in the helmet, and save your current location information in a wheelchair and speed information that is passed by smartphone to take advantage of the Black Box App and radio feature multi-Communications App S/W development.The results of this study can be utilized effectively a pseudo-real-time information can be shared in each other's wheelchair with many people moving. Limitations of the study at the Institute of Experimental concrete measures for the commercial approach to the development of operational models as required.

• Journal of the Semiconductor & Display Technology
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• v.9 no.1
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• pp.67-71
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• 2010

Head up display’s cooling system is auto-diagnosed resulting from the external environment. The quantity of heat depending on this Head up display’s cooling system layout determines the speed of FAN for system cooling. In other words, a system’s heat quantity is planned through the air density depending on altitude, the amount of wind in air depending on FAN control condition, and the algorithm that is proportional to delta temperature. To detect the altitude, we use the criteria of delta T, which is determined by the subtracted value of LED junction temperature, and atmospheric temperature that is recorded on the Head up display system. Depending on the classification of delta T value, the altitude section is determined. While we can use GPS as the tool to detect the altitude, we should predict the change of the air density as the altitude alters, and should not just measure the altitude. And the value of delta T is used as the criterion of detecting the altitude for increasing the cooling efficiency of the car’s inner Head up display system with reflecting the speed of the FAN dependent upon the air density. In our theory, altitude is depending on the value of delta T and stabilizing or maintaining the system’s temperature by changing FAN’s rpm depending on determined value of altitude.